Hydraulically damped spring-biased pistons and cylinders



Sept. z2, 1959 Filed April l5, 1957 E. M. MASON 2,905,458

HYDRAULICALLY DAMPED SPRING-BIASED PISTONS AND CYLINDERS 2 Sheets-Sheet1 EDWARD M. MASON 4ATTORNEY Sept. 22, 1959 E. M. MASON HYDRAULICALLYDAMPED SPRING-BIASED PISTONS AND CYLINDERS 2 Sheets-Sheet 2 Filed Aprill5', 1957 FIG. 7.

i NV E NTO R EDWARD M. MASON www FIG. 6.

ATTORNEY United States Patent OFP HYDRAULICALLY DAMPED SPRING-BIASEDPISTONS AND CYLINDERS Edward M. Mason, St. Johns, Mo., assignor toIinpax,

2 Claims. (Cl. 267-1) This invention relates in general to springdevices and, more particularly, to a hydraulically damped springbiasedpiston and cylinder.

Spring operated, hydraulically damped devices are sometimes employed inmechanical toys, such as, for example, in a toy dump .truck forelevating the dump body. Similar devices also nd use as door closers, inwhich case the opening of the door compresses a yspring so as toenergize the device, which energy is later released to provide apositive means for slowly closing the door. These devices usually employa spring-biased piston and cylinder arrangement wherein the cylinder islled with hydraulic fluid so as to provide a damping action whichretards the movement of the piston as it is forced along the cylinderunder the action of the spring. The piston and cylinder are usuallymachined to very close tolerances so that, upon movement of the pistonwithin the cylinder, the damping action is provided -by reason of thehydraulic uid gradually moving from one side of the piston to the otherthrough the small clearance space between the piston and cylinder as thepiston travels within the cylinder. However, notwithstanding the use ofvcarefully selected tolerances between the piston and cylinder, it hasbeen found 4that frequently the piston will tend to bind within thecylinder, thereby causing the piston to chatter as it moves.

It is, therefore, a primary object of the present invention to provide ahydraulically damped spring-biased piston and cylinder wherein thepiston is -freely slidable and will move smoothly without chattering or-binding within the cylinder.

It is also an object of the present invention to provide a device of thetype Astated which is inexpensive to construct by reason of the factthat component elements can be impact extruded and thereby precisedimensional tolerances can be achieved very economically.

With the above and other objects in view, my invention resides in thenovel -features of form, construction, arrangement, and combination ofparts presently described and pointed out in the claims.

In the accompanying drawings (two sheets)- Fig. 1 is a perspective Viewof a hydraulically damped spring-biased piston and cylinder constructedin accordance with and embodying the present invention;

Fig. 2 is la sectional view taken along line 2-2 of Fig. l, and showingthe device in fully extended or expanded position;

Fig. 3 is a sectional view, similar to Fig. 2, and showing the device infully contracted position;

Figs. 4 and 5 are longitudinal sectional views of the cylinder andpiston, respectively, forming part of the present invention and showinga-n intermediate stage of manufacture of the invention; and

Figs. 6 and 7 are sectional views, similar to Figs. 2 and 3, and showinga modied form of the present invention.

Referring now in more detail and by reference characters to thedrawings, which illustrate practical embodi- Patented Sept. 22, 1959 ICCments of the present invention, A designates a hydraulically `clampedspring-biased piston and cylinder device comprising a hollow cylinder 1`formed preferably as an impact extrusion and provided at its lower endwith a thickened portion 2 which forms a lshoulder 2', and at its lowerend the thickened portion 2 is provided with an axially extending bore3. At its upper end, the cylinder 11 is conically flared outwardly at 3for reception of a cap 4 having a conically tapered side wall 5 whichmatches :the taper of the ared portion 3'. The flared portion 3" is bentover to form an annular retaining lip 6 whereby the cap 4 is held snuglyand retentively in place. On its outwardly presented surface, the cap 4is integrally provided with a lug 7 having an aperture 8 drilledtherethrough by which one end of the cylinder 1 may be bolted, pinned,or otherwise secured to a suitable supporting surface (not shown).Mounted within the cylinder 1 Ifor reciprocating movement therein is aplunger assembly 9 including a hollow tubular piston rod 10 whichprojects through the bore 3, the latter being provided with an annulargroove 11 for reception of a seal-forming O-ring 12 which bears againstthe outer surface of the piston rod 10. Adjacent its upper end, thepiston rod 1t) is integrally provided with a plate-like piston 13 whichis sized to conform substantially to the inner diameter of thecylinder 1. At its outer periphery, the piston 13 is provided with anannular groove 14 for snug-fitting reception of an O-ring 15, the latterbeing adapted to provide a seal between the piston 13 and the innersurface of the cylinder 1. At its outer end, the piston rod 10 is swagedover to provide an arcuate valve seat 16 for reception of a ball-typecheck valve 17 which Ibears thereagainst, the valve 17 being providedwith a -diametrally extending aperture 18. Intermediate its ends, thepiston rod 10 is provided with a shoulder 19 for supporting one end of asmall coil compression spring 20, the other end of which bears againstthe ball valve 17 and normally urges said valve 17 against the arcuateabutment 16. The spring 20 is integrally provided with a short, axiallyextending rodlike extension 21 which Iprojects loosely through theaperture 18 in the ball valve 17. At a short distance below the piston13, the piston rod 10 is provided with idiametrally opposed ports 22,23, for communication between the interior of the cylinder 1 and theinside of the hollow piston rod 10. Provided for sliding movement withinthe piston rod 10 and below the shoulder 19 is a small slidableauxiliary piston 24, the outer periphery of which is grooved forreception of a pair of spaced parallel O-rings 25, 26, which form a sealbetween the auxiliary piston 24 and the interior wall of the piston rod10, and disposed between the piston 24 and the lower end wall 27 of thepiston rod 10 is a coil spring 27', the latter normally bearing againstthe auxiliary piston 24 and biasing it in the direction of the piston`13. Extending between the piston 13 and the cap 4 is a strongcompression spring 28 which urges the plunger assembly 9 to the positionshown in Fig. 2, so that the piston 13 seats on the shoulder 2. At itslower end, the piston rod 10 terminates in a lug 28 having an aperture29 by which the piston rod can be `secured to a suitable supporting sur-`face (not shown). Slightly above the lower end wall 27 the piston rod10 is provided with an air vent 29" for permitting communication toatmosphere from the lower side of the auxiliary piston 24. i

In the manufacture of the device A, the cylinder 1 and the piston rody10 and its associated piston 13 are impact extruded so as to providethe two components shown in Figs. 4 and 5. The cylinder .1 so formedincludes an extension 30, while the piston rod 10 is formed withconcentric axial extensions 3,1, 32, the latter, in effect, being anextension of the piston 13. In forming the completed plunger assembly 9,the spring 27 fol- 3 lowed bythe auxiliary piston' 2'4 are placed withinthe hollowA piston rod1'0; whereupon' the spring 20 and' ball' checkvalve 17 are placed within the piston rod 10 with the rod-like extension21 projecting through the. aperture y 18% Iliegaaiial extension' 31istlvie'n" swagdove to formi.

ther/alivia:seat 16'l` previously' described. The a'xial extensionn is'thenV4 bent` over toY form the annular groove 121" aridx the Gering 15'is' mounted therein.. `The axialextension 3`0ftof` the. cylinder 1`i's`bent inlvvardlfyV to form" the' groove: 11, whereupon lthe O-ringv12"i's fittedtherein; Theplunger assembly 9 is then placed within the;cylinder' 1 vso` as: toassume the relativepositions shown in. Fig. 2;The ball valve 17' is thenY depressed with al suitabletooland oil orother hydraulic' liuid isrthen pouredi'nto the open end of thecylinde'r,`.whereupon"the oil" will pass through the aperture 18" and'iill the porftin"of" tl'1`e.piston rod 10` abovethe auxiliary piston.2Q'. Oil' will"also`pa`ss` through the ports 22, '23,v and;l iill`the,

cylinder-1J on the lower" side of the piston 13;V 'I'hecoil" spring' ZBis then inserted' within the cylinder f1' and" theY remainder of thecylinder I above 'the piston 13^ille`d withoil,` whereupon the cap4 4is-iittedin'the' end ofthe cylinder' Il In this connection, itshouldhen'otedfthzlt-A si'ricetlie cap fisV formed with a conical surface 15",.the placement. of the cap 4 within the cylinder flwllreshape theeiidj'ofthe cylinderto form thenia'tcliingfii'ared.L pore tion 3,whereupon the end of the cylinder"l I bentV scribedf InV use, thedeviceV A is normally in theY position shown` inf Fig.` 217 However,whenA the plungerasseinblynfis moved from the position shown in Fig. Zto thatlshow'n in Figl 3, the coil Vspring 2-8` will. be compressedandopen the check valve 17 to permit oil to. flow therethroughandthrough theports 22, 23,'. to-ll the cylinder'l l1; onthe lowerside'of'fthe piston 13;- Since the. hydraulicvuid. is

relatively incompressible, the volume occupied by the ,y

pistonrod'l will. causelnan increase in the pressurewithin the cylinder1i on the lower side of the piston 13.

However, this increase in pressure is` relievedby virtue of suolivpressure acting. on the upper surface of the` auxiliary piston 24. andforcing the-.piston` 24 downvvardly4 against andcompressing the coilspring 27'. Upon re'- pass through thel ports 22, 2.3, `and Yseepslowly-through the aperture18 inthe ballvalve 717 -toprovide a damping`action.

It is. also possibleY to provide a modihed form'ofhwy-l draulicallydamped spring-biased piston' and cylinder device Al of the type shown inFigs. 6- and-7"- The devicefA! is similar to thev device' A, previouslydescribed;

However, in this form of the invention the auxiliary'V piston. 24 and`spring' 27 employed in the device: Aareeliminated and the compressionspringZOf' is supportedW at. its lower endby means of a pin 33y securedin, and extending` diametrally through,A the pistonrod-flf'., In

assembling the device- A', the plunger assembly 9 is placed within thecylinder 1 in the manner shown in Fig.'A 6, whereupony the ball valve17" is .depressed'fby any' suitable,tv tool anda measuredfamontofoilrisffpoured into-thecylinderfl' so as to completely lill vthe hollowpiston rod and also the'lower. end ofthe'cylinder 1,"

to a level above the ports 22.', 23', such as shown in Fig. 6'; The'compression spring 28" i'sthen inserted into the cylinder 1 and theremainder of the cylinder 1' above the piston 13 is lled with oil,whereupon the cap 4 is placed in the cylinder 1 in the same manner as inthe device A, previously described. An air space a will then be formedbetween the oilfini'the. lower part of the cylinder andthe. piston 1.3,.so that whenl the plunger assembly 9" is' mved from thepositionshovvn-in Fig.l 6) to the position shown in Figi 7,theinc'rea'se in'pressure due to.' the'volume:o'ccujgxieil` by .thepiston. rod- 10" will; bei' oompesatedl forv by'f'reasorr or rhefaeethatL the' air in the spaee-a/willbe compressed. and consequently'reduced in volume, suoliA as showniri Fig'. 7.

It should be understoodfthat/ changes and modications in the form,construction, arrangement, and combination of the several parts of thehydraulically damped spring-'biasedV piston and the cylinder maybe madeland substituted for those hereinY shown yand describedwithout'departin'g from' the n'atine` and principle of my in# ventiom nv I Y' llavi'rig` thus described? niv" invention, what I. claim anddesire to secur'eby Letters Patent is;

` k'l-i.. A device ofthe',leliarasterdescribed.adapted` for useY iiiAmechanical toys and the like,l said! device comprisingl af cylinder.containingy hydraulic. a. piston. mounted for shiffing'. movement withinthe cylinder and being` sealed with respect. thereto, a compressionspringv interposedbetween the. piston. and oneenii of theoylindeg a;

rod extending;` from the.' piston and being", provided with a1 leastone. port therein. by which hydrauf licffliiidcan'owinto andout` of thepiston rod, achecle valve mountedinsaidv piston rod. andhaving.anaperture,L

extendingi th'eretliro'uglrl and. spring means biasing. said checkvalve, against andy closingoif one end of thepiston'r rod, said-Y(spring means' having a projection passing;`

loosely/through said. aperture.

2:l A devicelo the character.described;adapted-forfuse,` in. mechanical:toys andE the like, saiddevicev comprising aJMcylinder'containing.hydrauliciluid, a piston mounted.

forfnshiftingr movement withinthe cylinder and'being;

sealed with.. respect.V thereto, a compression' spring; Vinterposedbetween the piston and one end of the cylinder, aA hollow` pistonv rod,extending frornther piston and being providedwith-V at least oneportytherein by which' hydrau-i lic fluid-'can flowA into and out of thepiston rod, Vacheck valve mounted in.r saidpiston rod and having-anaperture,

extending therethrough, spring means biasingsaidehecl Val-ve against andclosing oi one end` of the. piston' rod,

saidvspring'rneansI having' 'a projection passing'` loosely through saidaperture, an; auxiliary.y piston slidably mountedA in the hollow piston:rod'andbeingini spaced relation tol l said check valve, and means forbiasing-the auxiliary piston. insthedirection of'. the check valve.

nefereneesvcaea insieme @fairs patent' UNITED STATES." marinus

